Do Delphi class vars have global or thread local storage?

Question

My guess is that class variables ("class var") are truly global in storage (that is, one instance for the entire application).

But I am wondering whether this is the case, or whether they are thread in storage (eg similar to a "threadvar") - once instance per thread.

Anyone know?

Edit: changed "scope" to "storage" as this is in fact the correct terminology, and what I am after (thanks Barry)

Answer 1

Yes, class variables are globally scoped. Have a look in the RTL source for details of how threadvars are implemented. Under Win32 each thread can have a block of memory allocated automatically to it on thread creation. This extra data area is what is used to contain your threadvars.

Answer 2

Class variables are scoped according to their member visibility attributes, and have global storage, not thread storage.

Scope is a syntactic concept, and relates to what identifiers are visible from where. It is the storage of the variable that is of concern here.

Answer 3

Class variables are just like classes: global and unique for the application.